Inquiring Minds

Questions About Physics

Electro-magnet

Dear Sir,
I have been set a physics assignment and I need to find out why the current effects the strength of an electro-magnet. If you know the answer I would really appreciate it if you could send it to me. That would be awesome.

Thanks Luke

Luke -

Hello. I am a scientist here at Fermilab and your question got forwarded to me. In some sense it is a question with an easy answer, but like most science, you can keep probing the answer until you reach a question that can't be answered. I'll give it a try:

An electromagnet uses a current of electricity to form a magnetic field.
Usually this magnetic field is 'funnelled' and concentrated through iron
or some other magnetic material. The basic properties of electromagnetism
were determined first by Ampere & Oersted in the 1820's and then by the
great Faraday in the 1840's. These guys were experimentalists and they
found that a changing electric field (like a moving electron in a wire)
can cause a magnetic field and that a changing magnetic field (like a
dynamo moved by a waterfall) can create an electric field. The two types
of fields are intricately coupled. Thus, if a changing electric field
causes a certain level of magnetic field, then twice that electric field
causes twice the magnetic field. The mathematics of electromagnetism were
set down in a very nice mathematical form by James Clerk Maxwell in the
1860's and we still use them today. However, the big question is: what
is a field? Today we regard fields as related to exchanges of fundamental
particles like we study at Fermilab. However, even with all my study of
physics, I'm afraid I can't really explain what a field 'really' is.

Hope this helps. Feel free to ask me about anything else you are concerned about.